1. Field of the Invention
The present invention relates to a substrate processing apparatus for performing prescribed processes on a substrate.
2. Description of the Background Art
A substrate processing apparatus is employed for performing various processes on a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, a photomask or an optical disk, or the like. In a process of fabricating a semiconductor device, for example, a substrate processing apparatus prepared by unifying respective ones of a series of processes and integrating a plurality of substrate processing units with each other is employed for improving production efficiency.
In a photolithography step, the substrate processing apparatus performs various types of substrate processes around an exposure process, and an exposure apparatus performs the exposure process. In this case, the substrate processing apparatus is provided with various substrate processing units such as a spin coating unit (spin coater) for applying a photoresist to the substrate, a spin developing unit (spin developer) for developing the substrate, a heating unit (hot plate) for heating the substrate and a cooling unit (cooling plate) for cooling the substrate, and a substrate transport unit for transporting the substrate between the substrate processing units.
On the other hand, the exposure apparatus comprises an exposure part such as a reduction project exposer (stepper) or the like, an alignment mechanism for positioning the substrate for the exposure part to print an exposure pattern thereon, a transport robot for transporting the substrate in the exposure apparatus, and the like.
In the photolithography step, the substrate processing apparatus first processes the substrate before the exposure process, then the exposure apparatus exposes the substrate, and thereafter the substrate processing apparatus processes the substrate again. Therefore, the substrate needs to be transferred between the substrate processing apparatus and the exposure apparatus. For this reason, the substrate processing apparatus is provided with the substrate transport unit for transferring the substrate. This substrate transport unit is called an interface unit (hereinafter referred to as an IF unit).
FIG. 1 is a plan view of a conventional substrate processing apparatus 200 comprising an IF unit 180, and FIGS. 2 and 3 are front and side elevational views of the IF unit 180 shown in FIG. 1 respectively.
Referring to FIG. 1, the substrate processing apparatus 200 comprises a plurality of spin coating units 160a, a plurality of spin developing units 160b, a substrate transport unit 170 and the IF unit 180. An exposure apparatus 300 is provided on one end portion of the substrate processing apparatus 200, to be adjacent to the IF unit 180.
The substrate transport unit 170 has a substrate transport robot 171 for transporting each substrate W in the X-axis direction (along arrow X). The IF unit 180 has a substrate transport robot 181. The substrate transport robot 181 includes a substrate holding part 182 for holding the substrate W, an X-axis direction moving mechanism 183 for moving the substrate holding part 182 in the X-axis direction, a Z direction moving mechanism 184 for moving the substrate holding part 182 in the Z-axis direction (along arrow Z) through the X direction moving mechanism 183, and a Y direction moving mechanism 185 for moving the substrate holding part 182 in the Y-axis direction (along arrow Y) through the Z direction moving mechanism 184 and the X direction moving mechanism 183.
Thus, the substrate transport robot 181 holds each substrate W on the substrate holding part 182 and moves the same in the X-, Y- and Z-axis directions, so that the substrate W can be transferred to and received from a substrate transfer table 190, a substrate introduction table 191, a substrate discharge table 192 and a buffer part 193.
The substrate transfer table 190 is employed for transferring and receiving the substrate W to and from the substrate transport robots 181 and 171. The substrate introduction table 191 and the substrate discharge table 192 are employed for transferring and receiving the substrate W to and from the substrate transport robot 181 and a substrate transport robot (not shown) provided in the exposure apparatus 300. As shown in FIG. 2, the IF unit 180 is provided on its side surface with an opening 186 for transferring and receiving the substrate W to and from the exposure apparatus 300. The buffer part 193 is employed for temporarily storing the substrate W when a difference is caused between processing times in the substrate processing apparatus 200 and the exposure apparatus 300.
In this substrate processing apparatus 200, the substrate transport robot 171 of the substrate transport unit 170 places the substrate W processed in any spin coating unit 160a on the substrate transfer table 190. The substrate transport robot 181 of the IF unit 180 receives the substrate W placed on the substrate transfer table 190 for holding the same in the substrate holding part 182, and places the substrate W on the substrate introduction table 191. The substrate W placed on the substrate introduction table 191 is introduced into the exposure apparatus 300 by the substrate transport robot provided therein.
The substrate W exposed in the exposure apparatus 300 is discharged from the exposure apparatus 300 by the substrate transport robot provided therein, and placed on the substrate discharge table 192. The substrate transport robot 181 of the IF unit 180 receives the substrate W placed on the substrate discharge table 192 for holding the same in the substrate holding part 182, and places the substrate W on the substrate transfer table 190. The substrate transport robot 171 of the substrate transport unit 170 transports the substrate W placed on the substrate transfer table 190 to any spin developing unit 160b.
In general, the time required by the exposure apparatus 300 for exposing the substrate W is longer than the times required by each spin coating unit 160a and each spin developing unit 160b of the substrate processing apparatus 200 for processing the substrate W. Particularly in case of processing a substrate having a large diameter of 300 mm, the exposure time in the exposure apparatus 300 is increased.
Thus, the throughput of the conventional substrate processing apparatus 200 is incoincident with that of the exposure apparatus 300, and hence the operating efficiency of the substrate processing apparatus 200 is disadvantageously reduced.